The present invention relates generally to feed controls over minute floating objects that spread in the fluid. The present invention is suitable, for example, for a feed controlling apparatus and method that feed minute floating cells in a drug discovery system that investigates reactions of biogenetic cells, such as leukocytes' antibody generations, for use with a medical field. The “drug discovery system”, as used herein, generally means a system that processes a cell, e.g., injects extrinsic gene and medication solutions using a fine needle or a capillary into a cell, then cultivates each processed cell, independently evaluate or process the cell (e.g., by screening and antibody extraction).
Recently, opportunities of using cells, to which gene and medication are injected, have increased in the field of regenerative medicine and genome-based drug discovery, etc. Unlike the research application, it is necessary in this medical application to previously determine a combination between a cell and an introduced material and to independently evaluate each cell, e.g., observe whether or not there is an effect expression in a single cell. In addition, the medical application requires a predetermined throughput to be maintained in processing a large amount of cells.
A transgenetic method includes a biological approach, such as a vector method, a chemical approach, such as a transfection, and a physical approach, such as an electroporation, a particle gun and an injection. The biological and chemical approaches are not suitable for the medical application because they limit combinations between cells and introduced materials. On the other hand, the physical approach is known as a method that does not limit the combinations. In particular, the injection approach (see, for example, Japanese Patent Applications, Publication Nos. 5-192171, 6-343478 and 2000-23657) has a high introduction success rate as widely used for artificial inseminations, and is likely to be adopted as a next-generation transgenetic method. According to the prior art injection approach, a skilled operator uses a microscope to introduce a material from a needle tip into a cell while minimizing damages to the cell.
Other prior art include, for example, Japanese Patent Applications, Publication Nos. 6-225750 and 5-18887.
However, the conventional injection approach has a problem of a low throughput, since it needs manual operations to a laboratory dish under the microscope field, and manual feeding to an incubator after the gene is injected. Therefore, the conventional injection approach is suitable for an environment that handles the small number of necessary cells as in the artificial insemination, but unsuitable for industrial applications, such as the regenerative medicine and genome-based drug discovery. In addition, the conventional injection approach handles cells that are irregularly arranged in a laboratory dish or a group of introduced cells, and has difficulties in independently evaluating each cell as required by the medical application.